Deep fryers are commercially used by restaurants, institutional kitchens, and fast food establishments for cooking a variety of food products, such as french fries, fish, fried chicken, and the like. The food product is cooked by totally immersing it within a vat or tank that is filled with heated oil or shortening. The oil may be heated using a flow of heated fluid, or gas, that is forced or drawn through a heat exchanger having flow passages that are located within or external to the cooking vat. A gas burner is provided to heat the gas circulating within the heat exchanger.
Generally, in such deep fryers, the heated fluid flows through the flow passages from an inlet to an outlet before being exhausted into the atmosphere. Some of the heating systems of the prior art can be extremely inefficient, however, and the average temperature of the exhaust gas is still extremely hot, on the order of 1200.degree. F. Due to the relatively short period of time in which the heated fluid actually remains within the flow passages, the heat transfer to the cooking oil is thereby limited, and potentially usable heating energy is wasted by being exhausted into the atmosphere.
U.S. Pat. No. 5,417,202, assigned on its face to America's Favorite Chicken Company (AFC) discloses a heat exchanger for a deep fryer having a plurality of heat transfer tubes connected to a pair of mixing plenums. The mixing plenums increase turbulence and thoroughly mix the heat transfer fluid which is carried through the tubes into the mixing plenums and exits the mixing plenums in a direction 180.degree. from the direction it entered.
It is an object of the present invention to provide a deep fryer having an improved heat exchanger which reduces some or all of the aforesaid difficulties inherent in prior known devices and enhances heat transfer to the cooking oil. Particular objects and advantages of the invention will be apparent to those skilled in the art, that is, those who are knowledgeable or experienced in this field of technology, in view of the following disclosure of the invention and detailed description of certain preferred embodiments.